ROBINSON AND GREENMAN. — GENUS THIDAX. 5 



ous showy heads 10 lines to au inch in diameter, with dark purple 

 involucre and broad bright orange-yellow rays. — Galinsoga trilobata, 

 Cav. Icon. iii. 42, t. 282; But. Mag. t. 1895; Sweet, Brit. Fl. Gard. 

 t. 56. Sogalgina (rilu hat a, Cass. Diet. Sci. Nat. xlix. 397. — Valley of 

 Mexico, Bouvgeaii, no. 846; near Chapultepec, Schaffner ; and on calca- 

 reous bluffs. Flor de Maria, Pringle, no. 3148 ; also in Michoacau in 

 fields near Patzcuaro, Pringle, no. 4271. The form without any trace 

 of pappus does not appear to differ in any other particular. A specimen 

 cultivated in the Botanic Garden of Harvard University has leaves 

 oblong, subentire. 



= = Pappus about equalling or somewhat exceeding the achenes. 



5. T. balbisioid.es. Gray. Annual, much branched, pubescent : 

 branches divaricate or the lowest decumbent : leaves from lanceolate and 

 irregularly toothed to deeply ternately cleft or pinnately parted : heads 

 rather numerous, nearly or quite an inch in diameter, with convex or 

 conical disk and spreading showy rays : ligules (exclusive of tube) 2\ to 

 4 lines long, as broad or broader. — Proc. Am, Acad. xv. 39. T. coro- 

 nopifolia. Gray, 1. c, not Hemsl. Galinsogea halbisioides, HBK. Nov. 

 Gen. & Spec. iv. 253, t. 386. Sogalgina bulbisioides, Cass. 1. c. xlix. 

 398. — Originally collected in Guanajuato between the Valley of San- 

 tiago and Lake Palangeo, at 5,500 feet altitude, by Humboldt ^ Bonpland. 

 It is described and figured by Kunth, 1. c, as having entire or repand 

 ligules of suborbicular contour. No plants with this character have 



- since been observed, and we follow Dr. Gray in referring to the species 

 the following, which differ only in their more or less distinctly 3-toothed 

 rays : Schajfner s no. 238, and Parry ^ Palmer's no. 509, both from San 

 Luis Potosi. Nor does T. leptophylla, Gray (1. c. xxi. 391), from Chihua- 

 hua [Palmer^ s no. 425, and Pringle' s no. 769), ajjpear to differ by any 

 constant or satisfactory character. A form from San Luis Potosi, repre- 

 sented by Parry Sf Palmer's no. 508, has the ligules sometimes 3-toothed 

 and sometimes divided nearly to the base into 3 oblong lobes. This 

 plant was rather confidently referred by Dr. Gray (1. c. xv. 39) to T. 

 coronopifolia, but it differs from that species decidedly in its much imbri- 

 cated inolucre, with very unequal and rounded scales, and in its attenuate 

 chaff. Nor is the ligule strap-like. In stating it to be so Dr. Gray had 

 presumably observed only one of the long oblong lobes of a very deejily 

 trifid ray. 



6. T. petrophila. Distinctly perennial from a lignescent base : 

 stems several, very slender, erect or nearly so : branches ascending : leaves 

 very narrow, linear, entire, toothed, or with 2 or 3 short linear lobes : 



